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#190727 - 09/10/09 10:16 AM Designing/Building an F16  
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pilgrim Offline
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I sailed Hobie 16s for many years but stopped when my kids were born... now they are teenagers I find myself drawn back to the sea. Just designed and built a 21ft stitch and glue outrigger canoe to exercise with but have my eyes on an F16.

Looking at the Vipers and Blades that are in the club here, I want to try to design and build an F16 of my own design.

The materials I can easily get here in Singapore are clear NZ pine, meranti and meranti marine plywood ( thinnest 3.6mm ), divinycell PVC foam , epoxy resin, carbon fibre cloth ( 200g/sq m or 250 g/sq m ), glass cloth and kevlar and carbon tow. What would be the best option without having access to a female mold.?

I was thinking over male mold frames either
1) 6mm pine strip covered with carbon fibre 200g/sqm
2) meranti marine plywood sides with pine strip bottom and fibreglass ( lowest cost option )
3) 6mm divinycell cut into strips for planking and carbon fibre 250gm/sqm

4) Hot wire carve blue EPS foam into a boat shape and cover with carbon fibre cloth

what do you think?

Thanks in advance

Shane



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#190731 - 09/10/09 10:46 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Jalani Offline
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I know that Scott McCook has been experimenting with F16 building methods. Why not have a chat with him? Especially as he knows what is available in your locale.


John Alani
___________
Stealth F16s GBR527 and GBR538
#190736 - 09/10/09 11:07 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Mark P Offline
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I'd go with the lowest cost option
A) If you make a mistake during construction it wont cost too much
B) If you make a mistake with the design it wont cost too much
C) In a couple of years you may want to adapt the design or you may feel the construction is a little heavy or not stiff enough etc you haven't wasted too much money on your hulls
D) If it gets totaled due to a collision again you wont have wasted your money.
If it works first time and you have a fast F16 then you could always make another using more exotic materials.
In the mean time keep us informed on your decision


MP*MULTIHULLS
#190749 - 09/10/09 12:25 PM Re: Designing/Building an F16 [Re: Mark P]  
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Strip planking is very time consuming compared to bending divinycell/foam into a female mould and laminating. Ref: http://woodastic.blogspot.com/

If you go with ply, buy a sheet or two and check the quality of the wood, gluing and finished sheet. Check for delamination when boiling, voids, uneven layers of wood etc.

#190753 - 09/10/09 01:28 PM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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Mark P Offline
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A quote from a boat building website wink :
Murphy's law for boatbuilders is that you won't find your mistake until the glue has set, and Welsfords law for boatbuilders is that the mistake that can't be fixed with lots of epoxy and fibreglass hasn't been born yet.


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#190759 - 09/10/09 03:27 PM Re: Designing/Building an F16 [Re: Mark P]  
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Originally Posted by Mark P
A quote from a boat building website wink :
Murphy's law for boatbuilders is that you won't find your mistake until the glue has set, and Welsfords law for boatbuilders is that the mistake that can't be fixed with a hack saw, lots of epoxy and fibreglass hasn't been born yet.


Think you missed a bit Mark...... wink


F16 - GBR 553 - SOLD

I also talk sport here
#190795 - 09/10/09 09:40 PM Re: Designing/Building an F16 [Re: scooby_simon]  
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Heaps of ways to go about it. I designed and built a pair of F16 hulls out of foam and double bias glass in a female mdf jig.

But to go down this route you really need a fair bit of composite building experience or a helpful friend with said experience.

PM me if you need a hand with preparing the hull shape. I'm an engineer specialising in naval architecture and do that stuff all the time. Check out Gato's bloog on his F12 builds. http://www.gust.ax/

Oh, and don't go down the blue foam route. It might be cheap and quick to build but that'll probably be the only benefits with that method.

Last edited by ncik; 09/10/09 09:42 PM.
#190800 - 09/11/09 01:45 AM Re: Designing/Building an F16 [Re: ncik]  
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pilgrim Offline
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Thanks for the quick replies, its very encouraging...

J Alani,
I will ask Scott thanks.

Mark,
Point taken, I did waste a lot of time and money with my stitch and glue canoe. But it was fun designing, solving problems and building. What a change from my day job at the bank ( used to be an engineer but banks pay better)

Rolf,
I had heard a lot of bad stories about meranti ply in the US websites but I found the marine ply here to be of good quality. I went through several sheets when I built my canoe and there were no voids and good veneers used. Only thing is that the thinnest I could get was just under 4mm thick....and I dont think meranti ply bends as well as okuoume.

NCIK,
thanks for the offer, I will take you up on that. I am thinking the underwater cross section should be semi circular and the plan view of the hulls should be 2 circular arcs. So if I put the equation of a circle into a spreadsheet and vary the radius until I get the arc i want, I should be able to get a table of offsets of the width of the hull every ft. Then I draw a semicircle at each point to get the mold frames.



Last edited by pilgrim; 09/11/09 01:50 AM.
#190801 - 09/11/09 02:17 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Rolf_Nilsen Offline
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Originally Posted by pilgrim

I had heard a lot of bad stories about meranti ply in the US websites but I found the marine ply here to be of good quality. I went through several sheets when I built my canoe and there were no voids and good veneers used. Only thing is that the thinnest I could get was just under 4mm thick....and I dont think meranti ply bends as well as okuoume.



Why meranti? Few good experiences with meranti in high stress applications where you want low weight, as far as I know.
3.6mm is less than 4mm, so that further reduces strength. Are you planning on glassing the boat inside and out (adds weight)?

Last edited by Rolf_Nilsen; 09/11/09 02:18 AM.
#190802 - 09/11/09 02:53 AM Re: Designing/Building an F16 [Re: pilgrim]  
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I think on this site about 18 months ago, a group set themselves up via a blog site to design and build a F16 which would be made avaialble to all who were interested. I think a number of regular readers of this forum were involved, is that design still kicking about ?

Have a look at the method John Lindahl is campaigning in building his LR2 and LR3 A cats, gives a very strong structure and very light weight hulls plus it quite well documented. Google should find it no problem.

There is also a very good boat design and build section on this cat sailor forum at the bottom of the list of forums and also another good resource is /www.boatdesign.net/forums/

Best of luck but one tip, which is it going to be a single hander or a dual hander, they are quite different designs.

#190804 - 09/11/09 03:28 AM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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pilgrim Offline
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Originally Posted by Rolf_Nilsen
Strip planking is very time consuming compared to bending divinycell/foam into a female mould and laminating. Ref: http://woodastic.blogspot.com/


Rolf,
Your blog is very interesting since I have i have a supply of 6mm clear pine strips 5m long.... What cloth did you use for the outside and the inside of your Blade?

I made a fuselage for a scale model glider using balsa strip in the same way as you built your Blade - left /right halves but when it came to joining I had problems with warping/ twisting. Eventually I tapped them together and when it cured I discovered that the fuselage had a built in twist.... did you have any problems with twist in the left and right halves?

Thanks,

Shane

#190806 - 09/11/09 04:54 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Rolf_Nilsen Offline
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Originally Posted by pilgrim

Your blog is very interesting since I have i have a supply of 6mm clear pine strips 5m long.... What cloth did you use for the outside and the inside of your Blade?

160gsm I think it is. Dont remember exactly what we bought two years ago. We apply it +-45 deg to the wood fibers.
I would consider removing 1mm or even 2mm from the strips if I was going for a min weight boat, depending on the weight of the wood and how much epoxy it soaks up.
Strip planking is slow!

Originally Posted by pilgrim

I made a fuselage for a scale model glider using balsa strip in the same way as you built your Blade - left /right halves but when it came to joining I had problems with warping/ twisting. Eventually I tapped them together and when it cured I discovered that the fuselage had a built in twist.... did you have any problems with twist in the left and right halves?


We dont know yet. First match up is hopefully next week or the week after. It takes time to do 6 identical hull half panels but we are now almost done with panel #7 and well into #8.
As long as both sides are glassed the material is relatively stable. I have checked with experienced strip plank builders and they are in favour.

#190819 - 09/11/09 09:01 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Mark P Offline
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Before you get to carried away with your design Nick very kindly helped me with mine (still on drawing board, money being the main reason). I also initially thought of a semi circular hull cross section but after Nick crunched the numbers there wouldn't have been enough buoyancy. Now there is a relatively flat section to the bottom of the hulls.
The semi circular design had approx 250mm (10") of draft with 180kgs on one hull or 100mm (4")of draft with 80kgs on one hull.
The non semi circular design had 200mm (8") of draft with 190kgs on one hull or 120mm (5") with 90kgs on one hull, with a slightly wider flatter section between the Center board and Main beam the depth of draft would be even better.
I found an interesting article not so long back (can't find the link now) but instead of using foam (core cell) strips along the length of the hull they decided to lay a lot wider 600mm (24")foam vertically they reckon the benefits were stronger, lighter and fairer. I guess you have to be pretty handy with the hot air gun whilst forming the required curves in the core cell.


MP*MULTIHULLS
#190826 - 09/11/09 12:19 PM Re: Designing/Building an F16 [Re: Mark P]  
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pilgrim Offline
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keeping it semi circular would give the minimal wetted area and make it easy to do mold frames without CAD.
My proposal for the 16ft hull

max width 13.5 inch tapering to 1.5 inch at the bow and 10.75inch at the transom...

hull would be 19 inch high at the bow, 24 inch amidship and 14inch at the transom.

Max depth and height would be 5ft from the stern, coinciding with the middle of the daggerboard.

Would that work?

Shane

PS I can imagine using 24inch wide PVC foam... its quite stiff, how wil it conform to the curves of the hull....unless you have a female frame and apply heat while vacuuming it

Last edited by pilgrim; 09/11/09 12:22 PM.
#190834 - 09/11/09 05:31 PM Re: Designing/Building an F16 [Re: pilgrim]  
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Mark P Offline
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Shane
I'm a raw beginner when it comes to stuff like this!! So I'm basically repeating what I've heard in the past. As far as I can see if you're happy with your ideas then just go for it, you never know what the outcome will be. I just wouldn't like to see you wasting your time and money on a design which although could be easier to build doesn't perform so well on the water.
Your overall design dimensions to my mind aren't out of the ordinary so you'll have yourself a F16.....
Probably the best wet pussy you've ever ridden!! (friday night humour)


MP*MULTIHULLS
#190836 - 09/11/09 06:36 PM Re: Designing/Building an F16 [Re: Mark P]  
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lesburn1 Offline
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How about something like this.
I would go with a flatter bottom my self.
Where you put the center board is a function of where your center of life for upwind sail area is and how much weather helm you want.

Attached Files
F16_AA.jpg (1677 downloads)
F16_B.jpg (1461 downloads)
F16_C.jpg (1380 downloads)
Last edited by lesburn1; 09/11/09 06:39 PM.

lesburn1.blogspot.com

A-Cat USA 49
18Sq 49

member- Royal Society for Making Cool Stuff
#190855 - 09/12/09 09:41 AM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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pilgrim Offline
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Why consider meranti?
Its readily available here in Singapore and light red meranti is about the same density as pine. Its a bit brittle I hear but made into plywood that problem doesnt seem to manifest.

Why simple semi circular forms?
I couldn't find any plans for F16s on the Internet. So I want to make this design free and available for any home builder to build. In my other hobby, aeromodelling, scratch builders are a dying breed so I hope that all the scratch builders who are building kayaks and Moths will come over to cats so there is more info on the Internet.

MarkP,
What is the max width of your hull?

Shane

Last edited by pilgrim; 09/12/09 10:18 AM.
#190856 - 09/12/09 10:15 AM Re: Designing/Building an F16 [Re: lesburn1]  
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pilgrim Offline
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Wow Lesburn,
Thats very close to what was in my head. The only changes I would make are to have the for'ard sections go from vertical sides amidships to more of a teardrop section at the bow. that would reduce weight forward. And same for the after sections behind the trampoline so that if you trapeze way behind your footing is at a better angle to help from being slung forward in a near pitch pole. I think the Viper has a good design there.

i am thinking of adapting a method of building model airplane wings where you laminate a skin of glass/ wood strip on mylar sheets then vacuum bag to a flat surface. When cured, the mylar is peeled off, the sheet can be cut to shape and applied to the mold frames for the hull sides. It would still be flexible because only one side of the wood strips would have fibreglass, the other side would have the fibreglass applied after the rest of the sheeting is done. The advantage is that sheet has one side practically faired and finished because the mylar will leave a glossy perfectly smooth finish. If this method can be used for the hull sides, half the fairing is taken care of..

Still have to work out the details...

Need some info on scantlings..

For Okoume plywood F16s -
What weight of cloth is used and what thickness for the okoume plywood?

For strip planked F16s - What thickness wood and what weight cloth?

I can easily get Alumimium T5 hardness of circular section for the cross beams. Are these suitable? 100mmm or 125 mm?

thanks,
Shane




Last edited by pilgrim; 09/12/09 10:26 AM.
#190858 - 09/12/09 12:15 PM Re: Designing/Building an F16 [Re: pilgrim]  
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For strip planking: 4mm norwegian spruce and a layer of 160gsm cloth put on diagonally on each side of the wood. That is what we use.

For okume, you dont need glass as far as I know.

100mm beams are good.


One of my co-workers in the office is heavily into scale RC airplane models. He is putting the finishing touches on a Tiger Moth just now smile

#190869 - 09/12/09 06:34 PM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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Brett Goodall Offline
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Just some quick feed back on the lesburn design...

"Teardropping" the sections like pilgrim said would be good as it would improve the water line and decrease fore deck area.

Push the buoyancy forward. This design has no where near enough volume up front. This doesn't hurt the hydrodynamics of the boat and will give you more downwind stability. Just have a look at wing sections and how "full forward" they are.

The other recomendations if you are going to build an F16... keep the platform as stiff as you can, solid beams and stiff hulls.

Also, don't forget 80% of a boats performance comes from the rig... so give some thought to who will do this and how it will integrate with the platform design.

Besides that, I guess if you want to see how we think an F16 should be done, have a look at the VIPER.

Good luck and hope to see you on the water.

Last edited by AUS-CAT; 09/12/09 06:34 PM.
#190873 - 09/12/09 08:20 PM Re: Designing/Building an F16 [Re: Brett Goodall]  
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lesburn1 Offline
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That design was a quick throw together.
I am not in the boat design biz.
As to construction..
I have used 4mm okume ply for tortured wood construction in the past (a-cat and 18Sq) but for strip planking I think it would be to thin to get a proper tongue and grove joint. As to the beam issue I am using 4" (125+/-) .069 wall 6061 T6, these beams are leftover from an 18Sq project from 20 years ago. I am working on a oval carbon tube design to fit to my boat next year.
Coming from a 18Sq background (and having not sailed a cat with a crew in a very long time) I am unfamiliar with the dynamics of an F-16 so any thing I suggest should be take with a few grains of salt.

Last edited by lesburn1; 09/12/09 08:26 PM.

lesburn1.blogspot.com

A-Cat USA 49
18Sq 49

member- Royal Society for Making Cool Stuff
#190893 - 09/13/09 09:48 AM Re: Designing/Building an F16 [Re: lesburn1]  
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pilgrim Offline
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Thanks all. Will put something down on paper soon... this what I finished and launched last week...

[Linked Image]

#190909 - 09/13/09 08:50 PM Re: Designing/Building an F16 [Re: pilgrim]  
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Pilgrim

One suggestion I would make is to buy a used Taipan and use that as a base for you to build your F16. The hulls are one part of the whole package, and there are a lot of motivated sellers at the moment who have left or planning to leave Singapore and need to offload their boats.

Using this method you can learn how the platform works, how it all fits together, and then optimise your F16 with new hulls. Plus once you have finished your hulls, then you have the rest of the boat readily available. It may actually be cheaper, depending on the deal you make, to buy and build your F16 this way as opposed to buying all the parts and importing in seperately.

Getting a new mast in and buying all the blocks and ropes and sails can certainly add in costs quickly.

I am also in Singapore (sail the A-Cat and a Moth), but involved with Taipans for a very long time and F16s, so have a few ideas here.

Cheers
JC

#190914 - 09/14/09 02:56 AM Re: Designing/Building an F16 [Re: taipanfc]  
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pilgrim Offline
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HI JC,
Yes, it would certainly be easier and probaly cost the same but it wouldn't be as much fun. I sail occasionally with David Lee on his Taipan and he has offered me a share in his boat but I have this urge to try out my ideas and to build a boat. Its like an itch, if you scratch the wrong place you wont get rid of it....

My ideas are basically that for the hull, if you have a smooth curve to the underwater shape, correct volume distribution and a fair hull you have a good hull shape. Then you need to be at the minimum weight and the whole thing has to be stiff. A lot of the speed is in the rig but most of all the sailor.


DIY is a compulsion...

Shane

Last edited by pilgrim; 09/14/09 03:14 AM.
#190915 - 09/14/09 02:59 AM Re: Designing/Building an F16 [Re: pilgrim]  
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pilgrim Offline
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This is at table of the hull half-widths in inches, stations are 12 inches apart. The bow is Station 0. Above the datum line the hull can be vertical sided, below the datum line, the hull is a semicircle with radius as in the table. Its basically a circular arc, formula of a circle is r^2 = x^2 +y^2
y = sqrt ( r^2 - y^2 ) - put this into a spreasheet and input R=1410 inches and you get this arc...

HULL WIDTH 13.50 INCHES TRANSOM WIDTH 10.96
STATION 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
0.75 1.64 2.61 3.48 4.25 4.92 5.48 5.94 6.30 6.55 6.70 6.76 6.70 6.55 6.30 5.94 5.48

The bow will have a bulb of radius 0.75"



Last edited by pilgrim; 09/14/09 03:29 AM.
#190920 - 09/14/09 06:34 AM Re: Designing/Building an F16 [Re: pilgrim]  
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taipanfc Offline
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OK, no problem Shane. Good to hear you have the passion to go through with this. Know that space to build boats in Singapore is virtually non-existent since 90%+ of housing is apartments/flats.

There are a few boat owners who would be keen for any bid on their boats as some are no longer in the country, so thought cheap way to get the rest of the boat components.

But for build ideas, let me know if you want help as I have a few ideas of how to improve things. There are a few things that can be improved around the beams and boards which noone is really doing and quite hard to put into a production boat due to the tooling required, but can be utilised in a home build as you are doing everything from scratch.

Send me a PM if you want.

JC

#190994 - 09/15/09 05:22 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Mark P Offline
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Hi Shane
Unfortunately I don't work in inches, so the dim's for my single handed design are 300mm (12"approx) wide at the front beam, 295mm (11.75"approx) at the rear of the C/B case and 270mm (10.62"approx) at the transom.
The depth of the hull under the front beam is identical to both the Stealth, Auz Tool & Bimare AJ, roughly 460mm (18.25")


MP*MULTIHULLS
#191011 - 09/15/09 08:32 AM Re: Designing/Building an F16 [Re: Mark P]  
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pilgrim Offline
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Thanks Mark,
Your single handed design is slightly narrower and with less height which is to be expected. I am about 90kg and with a crew of around 50-55 kg I would need the extra volume. So far I think I am in the ball park....

Shane

#191012 - 09/15/09 08:40 AM Re: Designing/Building an F16 [Re: pilgrim]  
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pgp Offline
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crazy I have to ask, has anyone thought about flat bottom/hard chine?


Pete Pollard
Blade 702

'When you have a lot of things to do, it's best to get your nap out of the way first.

#191021 - 09/15/09 09:04 AM Re: Designing/Building an F16 [Re: pgp]  
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pilgrim Offline
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I did think about hard chine because its so much easier to build but I dropped it because of the following reasons -

Advantages of hard chine
- easier to build
- tracks better
- chine probably resists leeway

Disadvantages
- more wetted surface area
- cross flow is obstructed by the chine. I believe there is slip which causes the water flow to be at a slight diagonal to the axis of the hull. In a rounded hull, this is not a problem but for a hard chine I think the boat has more drag in some situations.
- looks amateurish next to the rounded white plastic factory jobs

I don't think it will make the boat faster but I chose round hull because I think it looks cool and I want to try and build it.

Shane

#191023 - 09/15/09 09:17 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Hard chines can look cool as well, if that is what is wanted. I dont know for sure how bad/well hard chine hulls will do compared to round hulls in real life.

#191179 - 09/17/09 08:07 AM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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Rolf,
what is the target weight for the each bare hull of your Blade? What size are your cross beams?

thanks
Shane

#191183 - 09/17/09 08:19 AM Re: Designing/Building an F16 [Re: pilgrim]  
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The target weight should be 23.5kg for each hull. We have not done a thorough calculation to try and predict our weight. One hull panel (one side of the hull) comes in around 8kgs on our scales. Add bulkheads, deck stringers, transom, decking, beam seats and eventual fittings.

Our beams will be 100mm in diam, carbon tube.

#191231 - 09/18/09 02:20 AM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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Thanks Rolf,
Thats something to strive for...but my calculations so far yield 25.5kg per hull... guess i have to thin the wood i will be using...myabe I will planedown the thickness at the bow and stern.

Carbons tubes are the ultimate!May I ask what weight of cloth you are using for the carbon beams and how many layers?
I assume you are going to bolt a traveller track onto the beam..

Shane

Last edited by pilgrim; 09/18/09 02:42 AM.
#191233 - 09/18/09 04:19 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Carbon tubes becouse alu tubes was more expensive than carbon. Believe it or not.
416gsm uni and regular 0-90. 5 layers is the current plan but will be re-checked before we wet out the epoxy. Currently testing the process and setup by making glass tubes. Much cheaper to do that wrong.

Traveller track will probably be glued and bolted.

#191241 - 09/18/09 07:27 AM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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Rolf, on the beams, are you going to glue them to the hulls or drill and bolt them? I would think glue would be the best way to go but then you can't get them apart easily either.


Blade F16
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#191244 - 09/18/09 07:51 AM Re: Designing/Building an F16 [Re: Timbo]  
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Originally Posted by Timbo
Rolf, on the beams, are you going to glue them to the hulls or drill and bolt them? I would think glue would be the best way to go but then you can't get them apart easily either.
And very illegal according the F16 class rules.

#191246 - 09/18/09 08:07 AM Re: Designing/Building an F16 [Re: Robi]  
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Well some day I might actually read all the rules...some day. ;^) I thought carbon beams were illegal as well? Or carbon anything?



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#191255 - 09/18/09 08:44 AM Re: Designing/Building an F16 [Re: Timbo]  
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Carbon is LEGAL, and I think if you wanted to, you could build the whole boat out of carbon if you'd like. At least, I think.


Mike


Viper USA 132

1984 Hobie 18
#191256 - 09/18/09 08:52 AM Re: Designing/Building an F16 [Re: mikeborden]  
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We are for sure going to bolt the beams to the hulls. Glued beams are somewhat impractical when it comes to long distance transportation and storage during winter.

#191257 - 09/18/09 09:01 AM Re: Designing/Building an F16 [Re: mikeborden]  
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Originally Posted by mikeborden
Carbon is LEGAL, and I think if you wanted to, you could build the whole boat out of carbon if you'd like. At least, I think.


Mike


At the moment carbon is legal. There was a proposal to ban it in the class with the reason being to try and keep costs in control.

I think the way the rules are currently written it does not matter. A min tip weight on the mast, min weight of the platform and non-glued beams pretty much makes the use of carbon a non-issue. The potential performance difference is limited with these rules and the cost to go with carbon is significant. If some one want to have bling they can, but IMO with these limits it still will not win you any races.

#191261 - 09/18/09 09:32 AM Re: Designing/Building an F16 [Re: Matt M]  
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Agree 100% with Matt on carbon use and the class rules.

Our carbon use is a special case due to some very special logistical issues. Like having to import suitable sections while the carbon weavers is in our backyard. Carbon beams is a really poor way to use carbon.

#191264 - 09/18/09 10:20 AM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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I think part of the reason for non-glued beams is that the width of the platform wouldn't allow the boats to fit into a container. Goodall was the one who pushed this from memory. A-Cats can get away with it as they are narrower and just can fit into a container.

#191266 - 09/18/09 10:52 AM Re: Designing/Building an F16 [Re: taipanfc]  
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Well Rolf, my only real concern here is about drilling holes into carbon tubes, through bolting them, and any potential crushing if over-tightened, or cracking if there is any slop, at the drilled hole area.

Are they (the tube builders) going to beef them up in the area of the holes to be drilled?


Blade F16
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#191273 - 09/18/09 11:37 AM Re: Designing/Building an F16 [Re: Timbo]  
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You are speaking with the tube builder to be grin
There will be compression chocks inside the tubes to handle compression loads and to stop any deformation. Just like what you find on a Marstrøm Tornado.

Drilling holes is not that bad, as long as there is no movement of the beams while they are under load. Overtightening bolts on beams is a big no-no in any circumstances. Stripped nuts inside the hull or crushed alu beams is no fun either.

#191274 - 09/18/09 11:38 AM Re: Designing/Building an F16 [Re: Timbo]  
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Carbon beams are legal. Glued in beams are not. That is where my illegal coment was coming from.

#191275 - 09/18/09 11:39 AM Re: Designing/Building an F16 [Re: Robi]  
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Finally some activity on the forum again. It has been way too quiet for some time now! smile

Since there is some interest on the topic, here is the post about the first test tube we made, in glass. Learnt a lot, but there is still more to learn before we wet out any carbon: http://woodastic.blogspot.com/2009/05/first-tube-test.html

#191313 - 09/18/09 06:23 PM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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Rolf - No 45 degree fibres in your beam? Might be trickier to build by hand but definitely better torsion properties with some.

#191322 - 09/18/09 10:45 PM Re: Designing/Building an F16 [Re: ncik]  
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There will be 45deg fibers in the beams, yes. Will have to lay up uni to do that. I'll dig out the lamination plan and post it before we go. Still building hull panels so the test tubes are a side project for now.

#191347 - 09/19/09 10:02 AM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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I got some Divinycell PVC foam to test out - 6mm H60. A bit underwhelmed... not the magic material I thought it would be - flexible, and feels soft wonder why it costs so much more than blue foam or foam core from the Art shop..

The best way I've seen for a home builder to do beams is by Dr Mark Drela of MIT. You need to get low temp prepreg carbon unidirectional and roll over an aluminium tube thats covered with mylar release film. You have to build a makeshift oven but it only needs 275 deg Fahrenheit. You need to bind it with shrink tape before you stick it in. First the outside heatshrink tape tightens, then the epoxy liquifies and the excess soaks into the paper as the carbon fibers get compacted, then the
epoxy gels and finally solidifies.
http://www.cstsales.com/carbon_prepreg.html

$40 per pound - maybe 7lbs per beam? $280 for hitech carbon beams...

Unfortunately, I dont think they can ship prepreg to Singapore since it needs to be kept refridgerated.

Shane

#191416 - 09/20/09 04:35 PM Re: Designing/Building an F16 [Re: pilgrim]  

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Pilgrim, the advantage of divinycell over your blue foam will be in the shear strength. This is the crucial property when designing a foam sandwich structure. The flexibility is actually an advantagous feature not only in building but also in the strength of the final structure is it means the skins will take the majority of the load instead of the foam. Most people would use primarily 80kg foam for your application. The 60kg will bruise easily unless you put a lot of glass/carbon over it.

#191456 - 09/21/09 10:22 AM Re: Designing/Building an F16 [Re: ]  
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Thanks Scarecrow, will keep that in mind. If I do use divinycell I will probably go all the way and use carbon fibre. The extra USD 1500 or so will repay itself if I ever want to sell the boat.. I love wood but people are unfairly prejudiced against wood in boats except for teak.

#192452 - 10/01/09 09:18 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Drew up the forms incorporating some of the suggestions that Ncik gave - more volume by using a constant radius circular chine and a narrower transom.. Here are the hand drawn forms... I now realise it looks weird because I dont have the waterline horizontal..the transom bottom should be aligned with the bottom of the bow
drats.. I
I'll redraw it tomorrow but now its late..
[Linked Image]

Last edited by pilgrim; 10/01/09 09:23 AM.
#192461 - 10/01/09 10:43 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Looks like a "modern" hullshape. I am not qualified to voice any opinion other than that. smile

Have you decided on a building method yet?


Keep it up, and do create a blog to document the process if you get to the implementation stage.

#192488 - 10/01/09 06:36 PM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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Looks pretty good.... the real trick now is to draw up the corresponding water line and kiel line and make sure you're happy with them.

Just another quick note, and this may happen later.... see if you can let the lines flow a little more.... not just straight line to a radius. This will make it easier to get a nice surface when you get to that stage. This is pretty important in CAD modelling but the same can be said in the real world.

http://en.wikipedia.org/wiki/Geometric_continuity

#192503 - 10/02/09 06:10 AM Re: Designing/Building an F16 [Re: Brett Goodall]  
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Hamburg
Try the other way around:
Fee!ship
or the free version of delftship. Don't ask me which one is better.

The basic idea is that you control the shape of the hull indirectly with a few parameters. Main characteristics as displacement, prismatic and block coefficient, water plane area etc. are immediatly calculated. As a result you get the section shape and a hull surface which fulfils geometric continuity. You can even check which parts of the hull are developable.
A few hours spend in lofting can save days in the workshop...

Cheers,

Klaus

#192529 - 10/02/09 10:59 AM Re: Designing/Building an F16 [Re: Smiths_Cat]  
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Thanks all, still a bit green so I will probably try to Keep it Simple.. Freeship is fun to play with and one day I will understand how to use it fully...

#192677 - 10/05/09 02:50 PM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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Hey Rolf, now that the word is out, we are all coming over! You got a couch? ;^)

http://www.msnbc.msn.com/id/33178495/ns/world_news/?GT1=43001



Blade F16
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#192710 - 10/06/09 12:02 AM Re: Designing/Building an F16 [Re: Timbo]  
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This probably belongs in that "drill" trainwreck of a thread smile
There is lots of room here and we could need some new people.. You are going to hate both the summers and winters though, especially if you settle north of the artic circle which is where there is a lot of room.

#192711 - 10/06/09 01:08 AM Re: Designing/Building an F16 [Re: Timbo]  
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Tim,
Rolf has a couch and plenty of whisky too!


I know that the voices in my head aint real,
but they have some pretty good ideas.
There is no such thing as a quick fix and I've never had free lunch!

#192713 - 10/06/09 02:09 AM Re: Designing/Building an F16 [Re: phill]  
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Yeah, that was a bit unfriendly of me smile

Of course I have a couch, I even have a full blown guestroom so it is possible to stay for quite some time. Please do come over but complaining about the weather is a "no no" (we are on the seventh week of rain and temps around 3-5degC now).
I can not seem to make a dent in the whisky department so any help there is appreciated. grin I am running low on the japanese "Gould&Gould" though.

#192715 - 10/06/09 03:11 AM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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Holland ranks as the 6th best country to live, its like Norway but warmer. grin
Forecast for tomorrow is 19c and 20 knot winds, too bad I have to work.
This summer has been extremely good anyway with some of the best sailing ever, I'm surprised we dont rank higher because of this.

Maybe we should make a list of which country is the best place to live for a sailor! smile

#192718 - 10/06/09 04:50 AM Re: Designing/Building an F16 [Re: Tony_F18]  
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pepin Offline
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France
Originally Posted by Tony_F18
Maybe we should make a list of which country is the best place to live for a sailor! smile
I'm Corsican. Best place for sailing ever.

But I live in the UK. Sometimes I'm wondering why.

#192719 - 10/06/09 05:44 AM Re: Designing/Building an F16 [Re: pepin]  
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couldn't resist it
Originally Posted by pepin
Originally Posted by Tony_F18
Maybe we should make a list of which country is the best place to live for a sailor! smile
I'm Corsican. Best place for sailing ever.

But I live in the UK. Sometimes I'm wondering why.


you wonder why ??? me too , If I had a chance Id be off from this "sinking Ship" we call the uk wink faster than a rat up a drain pipe

Corsica vs Uk no brainer

Last edited by Codblow; 10/06/09 05:45 AM.
#192725 - 10/06/09 06:18 AM Re: Designing/Building an F16 [Re: Codblow]  
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Originally Posted by Codblow
Originally Posted by pepin
Originally Posted by Tony_F18
Maybe we should make a list of which country is the best place to live for a sailor! smile
I'm Corsican. Best place for sailing ever.

But I live in the UK. Sometimes I'm wondering why.


you wonder why ??? me too , If I had a chance Id be off from this "sinking Ship" we call the uk wink faster than a rat up a drain pipe

Corsica vs Uk no brainer


There has to be a woman involved in that history. Corcica/France or the UK..

#192726 - 10/06/09 06:29 AM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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Rolf: I take it you have never been among the French grin

#192727 - 10/06/09 06:37 AM Re: Designing/Building an F16 [Re: Tony_F18]  
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Sure I have. They are an unique breed with good and bad sides like everybody else smile
The french endorse multihull sailing, got to like that.

Now corcicans I have never spent time with but they seems like an interesting people. A people unleashing Napoleon , being part of shaping king Carl Johan (http://en.wikipedia.org/wiki/Charles_XIV_John_of_Sweden) and inventing the "vendetta" must be quite something.

#192728 - 10/06/09 07:05 AM Re: Designing/Building an F16 [Re: Codblow]  
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Mumbles Y.C Wales U.K
I was wondering what it would take for you to re join us. I know that he who shouldn't be named hasn't been here for a long time but I wasn't expecting you to chime in on this thread. Welcome back Codblow, what happened at the Scottish Stealth Champs etc etc.


MP*MULTIHULLS
#192753 - 10/06/09 09:04 AM Re: Designing/Building an F16 [Re: Mark P]  
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I'm not going anywhere the water's cold... the tropics are where you want to sail. If you have to wear a wetsuit to sail you can keep it... Sydney or Hawaii is about the coldest I would go to sail....

Last edited by pilgrim; 10/06/09 09:06 AM.
#192773 - 10/06/09 12:15 PM Re: Designing/Building an F16 [Re: pepin]  
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Originally Posted by pepin

But I live in the UK. Sometimes I'm wondering why.


To be fair guys all us foreigners, be it NZ, French, Scotish, Welsh all live here by choice, no point wingeing about it. As to why, its called a good safe bet for work and employment with a safe bet of weather and housing.

Now for me those things never really came into it, just the best looking women in the world seem to walk up and down the streets on a daily basis smirk

#192775 - 10/06/09 12:26 PM Re: Designing/Building an F16 [Re: waynemarlow]  
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*cough* *splutter*.. there you go, now I have to wash my screen laugh laugh

#192788 - 10/06/09 02:06 PM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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When did Wayne move to Milan??

:^)


Blade F16
#777
#192792 - 10/06/09 02:55 PM Re: Designing/Building an F16 [Re: Timbo]  
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Originally Posted by Timbo
When did Wayne move to Milan??

:^)

Beauty is in the eye of the beholder but one should always look at the mother in law for future reference.

#192810 - 10/06/09 05:41 PM Re: Designing/Building an F16 [Re: waynemarlow]  
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Yeah, and I'm still looking to -behold- that gal with the green Nike's!


Blade F16
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#192813 - 10/06/09 06:23 PM Re: Designing/Building an F16 [Re: Timbo]  
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Brisbane, Queensland, Australi...
It has also been said that beauty is in the eye of the beer-holder...

#199499 - 12/25/09 01:42 AM Re: Designing/Building an F16 [Re: ncik]  
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pilgrim Offline
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Update of build - Cut out the frames [Linked Image]

#199500 - 12/25/09 01:45 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Built the mold using plywood. Flat sides make this easier and quicker to build. The key to boat building is finishing it before you run out of steam. [Linked Image]

#199501 - 12/25/09 01:49 AM Re: Designing/Building an F16 [Re: pilgrim]  
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I covered the mold with the plastic film that is used here to cover books, I think its PVC. Then my friend Kenn and I tacked the foam to the frame with nails.
[Linked Image]

#199502 - 12/25/09 01:53 AM Re: Designing/Building an F16 [Re: pilgrim]  
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The foam is roughed out using japanese Ryoba saw, 60 grit sandpaper and an Olfa paper cutter. At this stage I have only used a week of my annual leave... one more week and its back to work... [Linked Image]

#199503 - 12/25/09 02:11 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Technical stuff

Divinycell foam H80 thickness 10mm is used throughout except for the transom, major bulkheads and the area around where the centreboard exits which use H160 density.

Strip are cut to apporx 13-15mm width for strip planking using a large Olfa paper cutter and an aluminium channel for a guide. H80 cuts like medium density balsa wood and H160 like heavy balsa... no need to get a circular saw. No dust with a cutter...

I fiiled in the gaps in the strips with epoxy mixed with lighweight filler. I didnt edge glue it while assembling but put it all together with nails and tape and after the foam strips are in place I went over it with a spackle knife. On the first day I filled in the gaps between the nails and the tape, then after the epoxy cured 12 hrs later I removed the nails and tape and spackled the rest of the hull.

Applying plastic to the mold, tacking the foam to the mold and the first pass of spackling took a whole day working from 9am to 11pm with my friend helping me out for most of the time.

Shane

#199504 - 12/25/09 02:23 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Questions

I am planning to layup the foam using a single layer of 200g/sq m carbon cloth with a double layer in the centre of the hull from the chainplate area to the 1m for'ard of the front beam. Outside layer of carbon will be 0/90 in one layer ( the cloth is 1.5m wide ) and the inside layer will be -45deg/ +45 deg with a double layer in the centre of the hull from aft of the centreboard to for'ard of the front beam.

Is this enough?

I also plan to have a sheer clamp from Divinycell and cover is carbon fiber to help increase the gluing are when I glue the deck to the hull. An alternative is to use a timber sheer clamp instead. Any thoughts on this?

Thanks

Shane

#199548 - 12/27/09 04:31 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Looking good Shane.

Can't help with your questions, but for chainplate location, what have you referenced this against? If taken from the Taipan, then this can be moved further aft. Taipan location was to allow the main to get out as far as possible, as people were sailing straight downwind at the time of design. We no longer do that, so can move chainplate aft and this takes some of the load off the chainplate due to the triangle to hold the mast has a large base. Boyer tried to get the Taipan class rules amended to allow this about 7 or 8 years ago.

#199549 - 12/27/09 05:48 AM Re: Designing/Building an F16 [Re: taipanfc]  
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Wouter Offline
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Quote

Can't help with your questions, but for chainplate location, what have you referenced this against? If taken from the Taipan, then this can be moved further aft.



This is what I have done on my homebuild Taipan F16. I've repositioned the side stay 200 mm further aft and I have never experienced any negative effects. Even when sailing without a spinnaker the boom never seems to go out far enough to touch it. The sail may however, up top, but you'll sail with some very large amount of twist when that happens. My sailing style doesn't seem to include this profile and it almost never happens with me. Note, that I do sail a numbers of times without the spinnaker, when I just want to sail around for an hour or so and not do all the rigging work. Just throwing up the mainsail and go like an A-cat works well for the short sailing trips.

Main point of this post is however that in my opinion TaipanFC has a good point. You can place the sidestays further back without any penalty. The benefits in lower stresses and a more tight forestay are significant though. Going from 500 mm to 700 mm is a large modification.

Best of luck building your boat !

Wouter



Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
#199553 - 12/27/09 07:14 AM Re: Designing/Building an F16 [Re: taipanfc]  
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I was going to place the chainplate 68cm aft from the centre of the main cross beam which is the same as the Viper. Since I plan to use the Viper sailplan, mast and sidestays it would be easier to get the tuning done if I have the basic dimensions the same.

Shane

#199554 - 12/27/09 07:26 AM Re: Designing/Building an F16 [Re: pilgrim]  
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http://www.mcmc-uk.com/video/epoxy-foam.html

When you get to foils, this may help. Looks like a good way to build them. Especially to make them consistent.

#199555 - 12/27/09 07:26 AM Re: Designing/Building an F16 [Re: taipanfc]  
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Thread over at Sailing Anarchy about foil building, http://forums.sailinganarchy.com/index.php?showtopic=101093

#199556 - 12/27/09 08:02 AM Re: Designing/Building an F16 [Re: taipanfc]  
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Yes, I was talking to my composites supplier about the epoxy foam... trouble is I would have to make a female mold which is a bit troublesome. Unless I design the board to be used in a Taipan or Viper then I could have a sideline supplying boards to the Taipan or Viper fleet.

Retirement plan?

No, too early!

#199557 - 12/27/09 08:05 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Any ideas on where to put the main beam? In the middle of the boat, slightly forward or slightly aft of middle? I think the Viper has it 2 inch forward of the middle but I gather that the current thinking is slightly aft of the middle so that you get more hull forward of that mast which helps if you want to push it harder downwind.

Any thoughts on this?

Shane

#199588 - 12/28/09 10:16 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Applied the carbon fibre cloth yesterday. one piece of 200g/ sq m 2x2 carbon twill weave. Used too much epoxy because I didnt vacuum bag. Its just too big for one person to layup well... there are some bubbles which I have to fix.

[img:center]http://pics.livejournal.com/goodworks/pic/0000ayhh/[/img]

#199589 - 12/28/09 10:32 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Shane, I'm sorry you're not getting much response to your thread. Why not try Mike Shappell at the "Man Shed"?

http://www.catsailor.com/forums/ubbthreads.php?ubb=showflat&Number=199401#Post199401

Last edited by pgp; 12/28/09 10:33 AM.

Pete Pollard
Blade 702

'When you have a lot of things to do, it's best to get your nap out of the way first.

#199598 - 12/28/09 12:44 PM Re: Designing/Building an F16 [Re: pgp]  
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I guess people are busy with family, christmas etc.
Really impressed with what you've done in such a short space of time though Shane. Amazing!

I look forward to seeing pics of the finished hulls (as, I'm sure, do you!! smile )


John Alani
___________
Stealth F16s GBR527 and GBR538
#199611 - 12/28/09 04:15 PM Re: Designing/Building an F16 [Re: pilgrim]  
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Pilgrim, A few tips,

Carbon on the outside is very vunerable to chafe and wear from beaching etc, put a layer or even two or 3 in the susceptable areas such as the bottom and trapezeing feet areas of glass. It won't add much weight as it has the benefit of mopping up the excess resin from the carbon layup.

I simply wet out the carbon and then place a layer of glass over the top, squeegee ( using a plastic filler applier )the glass into the carbon and you can soon see if you need more or less resin. I tend to layup a heavy glass cloth and then a very fine layer as this tends to flatten out the twill and therefore you need less filler and paint. Enevitably when you are fairing the outside before painting you can rub through the glass but it is obvious where as the carbon is not and much easier to repair.

In relation to the beam, it really depends on whether you are intending to be a single hander or double. If single then you can place the beam way back as per the A Class but with a two hander it becomes impractical as you need to be able to get the crew through under the sail, Bitsa is a bit extreme and even single handed it is tight. There are other benefits to having the beams back such as you need less volume up front and in theory should be a better light air performer without sacrificing Spinny down wind safety. Again Bitsa seems really difficult to bury the front as the Spinny clew is only about 1 metre ahead of the front of the hull even with max length pole.

The rear beam is much more tricky as it is really dependant on your rudder system and how long the arms of the rudder connection bar is. The system I used of gantrying out the rudders is too time consuming and I'm not sure that practical. Stick with the conventional I would say.
Fire the questions off as I'm sure there will be an answer.

#199635 - 12/29/09 06:53 AM Re: Designing/Building an F16 [Re: waynemarlow]  
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Hi Wayne,
I do have a band of carbon cloth 100mm wide the length of the bottom and I plan to cover the whole hull with lightweight glass cloth. I have to get rid of some bubbles first... will cut an X shaped incision with my Dremel cutoff disc, fill with epoxy and put them back with a carbon cloth patch over it. Next time I will do the cloth in parts instead of one big 5m x 1.5m piece for the whole hull - I was too ambitious for a solo effort.

I do like the way your rudders are out back so you have good leverage on the tiller arms. I've been thinking how to do that with carbon rods and I might do something similiar.

Shane

#199682 - 12/30/09 05:56 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Originally Posted by pilgrim
Hi Wayne,
I do have a band of carbon cloth 100mm wide the length of the bottom and I plan to cover the whole hull with lightweight glass cloth. I have to get rid of some bubbles first... will cut an X shaped incision with my Dremel cutoff disc, fill with epoxy and put them back with a carbon cloth patch over it. Next time I will do the cloth in parts instead of one big 5m x 1.5m piece for the whole hull - I was too ambitious for a solo effort.

I do like the way your rudders are out back so you have good leverage on the tiller arms. I've been thinking how to do that with carbon rods and I might do something similiar.

Shane


Shane, using carbon as you intend can cause more problems than solve, a 100mm additional band without other layers transfering the load to the single layer, will cause such a hard edge between the layers that it will almost certainly crack the inner layer of the two. Always use carbon for stiffening and glass to transfer the loads + act as wear layer.

Everyone seems to think Carbon is the great thing to use, it very often is the wrong material and should be used with caution. An all carbon boat will weigh marginally less ( probably only 3 -4 kilos to a well built glass boat ( and how many of us are not 3 -4 kilos over weight ), cost 3 times more than glass, most certainly will be far less duriable and twice as hard to repair when you ding it.

#199684 - 12/30/09 06:38 AM Re: Designing/Building an F16 [Re: waynemarlow]  
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It is christmas time.. I think I am +5 kilos just from christmas with the family so I certainly dont worry about carbon smile

From the picture it is hard to say what is bubbles, what is distortion in the cloth and what is bubbles. I really liked the plants and the bamboo in the pic though as we have about 100cm of snow the last week. smile
Putting on the cloth in one piece is OK if you organize the work. Ie starting at the middle and working outwards to both sides with one batch of 100grams epoxy at the time. Kayak and canoe builders do it all the time. A slow hardener might be better if you find the epoxy kicking too fast.


You are working fast, hope to get an on the water report soon.

Wayne,

any hope for a followup on how your snuffer works and more pics?

#199692 - 12/30/09 09:21 AM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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Wayne,

Thanks for your input. I will have a glass layer over everything for wear resistance. I dont think carbon is that bad. In aviation , models and full size, there is ample use of carbon in staggered multiple layers that allow taper in skin thickness without hard spots and stress concentrations to develop.
I also thought about the placement of the main beam and decided to place it 5 cm aft of the center. I will keep the rear beam 2m aft of the main beam like the Viper which leaves me 40cm between the rear beam and the transom. Thats a bit short so I will have to engineer a gantry like the Bitsa.

Rolf,
The cloth was distorted in places when I was draping it dry over foam. I smoothed it with a wide brush after draping. I applied the epoxy working from the middle to the ends. I use a 24 hr cure epoxy so I had enough time but it was very tiring because of the sheer area of the hull. When I applied the epoxy with the plastic spackle knife over the cloth I noticed that parts I worked on before had 2-3 cm air bubbles that just kept on returning even after I smoothed them down repeatedly with the spackle knife. The curved hull bottom was not affected and only the vertical sides.Next time I will cover the hull in parts and vacuum bag the cloth to the foam.

Even with a flash coat of epoxy applied to the foam beforehand, I used much more epoxy than I expected. The cloth was not shiny after application so I dont think I flooded the cloth so it must be that the Divinycell soaked up the resin like a sponge. I am anxious to weigh the hull...


Shane

#199697 - 12/30/09 10:41 AM Re: Designing/Building an F16 [Re: pilgrim]  
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You might have closed the pores in the foam with thickened epoxy (epoxy+microballons) mixed to a slurry and applied before placing the glass. (20/20 hindsight is not difficult, especially not while behind the keyboard).
I dont have much experience in glassing foam parts without vacuum. With wood it is imperative to not glass while the temperature is rising. Outgassing from wood is a problem. I dont know if divinycell is similar. What I do know is that the more you work the cloth after epoxy is applied, the harder it becomes to do a good job. Pushing air into the cloth.
When applying cloth over large pieces, I find it best to roll it on really carefully. Cloth that have been folded is never 100%, neither is cloth that have had any kind of force applied to it as it stretches and wrinkles so easily.
If I can choose, I prefer to put on the glass in a horizontal position. I find it much easier to get a good result if gravity helps me. Draping/applying epoxy to the "bottom" of the part first will distort the cloth when you come to the "flat" hull side.
You probably know all this from your RC building. I am just throwing out information that might be useful for others reading the forum.

Did you weight the resin and cloth before applying? If you do, you can track your progress while applying the cloth.

I think you are doing well. Keep up your efforts and you will be sailing soon. We have spent 1.5 years on our strip plank boats..

#199737 - 12/30/09 09:25 PM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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I primed the foam with clean epoxy ie no filler... that might be my problem. Next time I will use epoxy + microballoons... It really soaks like a sponge. I used about 3kg of epoxy for 1.5kg of cloth ( 7.5 sq m x 200g ). I dont think the cloth was oversoaked because it had a matt appearance. I think the epoxy went in to the foam.

I have to keep up the momentum otherwise I will lose interest and that will be a disaster.

Shane

#199763 - 12/31/09 02:04 PM Re: Designing/Building an F16 [Re: pilgrim]  
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I would have sealed the foam as suggested.. a micro-balloon mix.. sanded smooth and then applied the cloth. Foam eats epoxy!!


good luck

#199809 - 01/02/10 09:25 AM Re: Designing/Building an F16 [Re: Stewart]  
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pilgrim Offline
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Happy New Year to all!

Figured out why I got the buubles under the cloth.

I started out by pouring epoxy from the top middle and worked my way to the ends. It was working great at first but as I worked to the ends, the action of pulling the resin down at the ends pushed the cloth towards the middle and caused the cloth to bunch up and buckle creating bubbles.

so to summarise the mistakes I made so far...

Mistake 1 - Used clean epoxy to prime the foam, should have used epoxy mixed with microballoons or Q cell.

Mistake 2 - Allowed the cloth to bunch up in the middle when applying epoxy at the ends during layup. Should either have used vacuum bagging or should have worked the spackle knife sideways towards the ends instead of top down.

Shane

#199911 - 01/05/10 06:13 AM Re: Designing/Building an F16 [Re: pilgrim]  
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I have started a blog and new pictures will be there.

http://goodworks.livejournal.com/

I do hope to get some answers to my questions but if I cant I'll just give it my best guess and move on... If the boat works others can follow and if it breaks I'll document what I think went wrong and how I intend to fix it. Its a bit disappointing how little detailed information is available.. so I hope that others who want to try homebuilding will have a path to follow.. albeit strewn with the debris of my failures and misteps.

Shane

#199914 - 01/05/10 08:06 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Looking good Shane. Sorry can't help with the technical details, never done what you are doing.

However, where did you the carbon from? XSP? Going to try an experimental mast on the moth so need to make a base for it.

#199929 - 01/05/10 11:10 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Originally Posted by pilgrim
I have started a blog and new pictures will be there.

http://goodworks.livejournal.com/


Great!

Originally Posted by pilgrim

Its a bit disappointing how little detailed information is available.. so I hope that others who want to try homebuilding will have a path to follow.. albeit strewn with the debris of my failures and misteps.


How about giving some of the builders/designers around a call, or take measurements directly off a boat if you need that kind of information.

Could you restate what you need to know? I'll fill in what I know or can find out. We want to keep you going on that project.

#199932 - 01/05/10 11:23 AM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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pgp Offline
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I think Phil Brander had an indepth site for building a timber F16.

Anyone know where it is?


Pete Pollard
Blade 702

'When you have a lot of things to do, it's best to get your nap out of the way first.

#199935 - 01/05/10 11:36 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Originally Posted by pilgrim
Its a bit disappointing how little detailed information is available.. so I hope that others who want to try homebuilding will have a path to follow.. albeit strewn with the debris of my failures and misteps.

Shane


Without wishing to detract from what Shane has already done, IMO there are a huge loads of information about on building in Carbon and Glass and even greater amounts on boat building in general, but it is a pain to find quickly and time consuming to piece together but then if it was all so easily available then we would all be building our own boats.

Shanes approach of just getting on with things is possibly the best way in reality as I seemed to spend far to much time researching things but I'm not sure it could lead to small mistakes that turn into major problems. Fortunately the type of small scale construction we are using is pretty forgiving and with just a bit of over engineering we seem to not break to many bits.

My recommendation to anyone contemplating building a boat is to look at the LR2 blog as a possible alternative method, it is a good and easy path to follow and builds pretty good boats relatively quickly. cool

#199941 - 01/05/10 12:42 PM Re: Designing/Building an F16 [Re: waynemarlow]  
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What Wayne said! (Unless you have perverse ideas about actually building becouse of the process and wanting to do something special like an F16 with the finish of a grand piano)
(And if Shane was building to plans, things might be a bit easier, but there would still be questions).


Here you go Pete:
http://www.thebeachcats.com/index.php?module=pictures&g2_itemId=11955

#199943 - 01/05/10 12:58 PM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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Thanks Rolf. Isn't it time to update the "View from the Office" thread?


Pete Pollard
Blade 702

'When you have a lot of things to do, it's best to get your nap out of the way first.

#199976 - 01/05/10 07:42 PM Re: Designing/Building an F16 [Re: pgp]  
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How about use this thread as a dumping ground of good links and information that would be useful to the amateur homebuilder. Can post a link, say what was good or bad, what worked, what didn't, improvements. Would go a long way to helping people like Shane who are starting out on these projects and help grow the class.

#199979 - 01/05/10 09:30 PM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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I tried to contact a designer but no response. I would even buy a set of plans for reference but nothing modern seems available eg Blade or Viper era. I took some measurements from a Viper because I plan to use Viper sailplan and mast. Chainplate distance from main beam = 68 cm, main beam to rear beam 2m.

Questions

1. please critique my layup plan. Using 200 gm per m carbon cloth over Divinycell H80 overall, with 30g /m glass over that for a better finish. 0/90 deg orientation on th eoutside , -45/+45 inside of the hull.

Doubler of 200 g carbon starting 2m from tip of bow to 1m from transom 0/90deg orientation .

Deck doubler of 200g carbon starting 1.5m from bow tip to transom 0/90 deg orientation.

Local reinforcement of 200g /sq m cloth under beams and chainplate area -45/+45 deg oreintation. Local reinforcement of 300g/ kevlar under beams, chainplate and forestay anchor point to insulate metal from carbon and provide protection.

2. Should I have a sheer clamp to attach the deck? Timber? or Divinycell foam?

3. Bulkheads under Main Beam and Rear beam. Should I use plywood ( 10mm? ) or 200g carbon/H160 foam/carbon sandwich ?

4. Deck hardpoint under the beams - should I have 10mm plywood replacing the H80 foam or can I use H160 to replace the H80 foam?

5. Thinking of a 10mm diameter solid carbon extrusion covered in kevlar for a sidestay anchor instead of a 2,5mm stainless chainplate. More for the 'cool' factor but also to avoid crevice corrosion in the stainless steel. Worth the trouble for the cool points?

6. Broad centreboard like the Taipan or High Aspect ratio like the Viper? Asymetrical or sysmtrical foils?

7. Should there be a bulkhead at the chainplate position?

8. Do I need diagonal stringers between bulkheads as a hull stiffener and to give torsional strength?

Thanks in advance

6.

#199983 - 01/05/10 09:52 PM Re: Designing/Building an F16 [Re: pilgrim]  
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Have the topsides of the bow quite rounded. Makes a big difference when you have buried the bows, helps them to recover.

High aspect boards is definitely the way to go. Does mean you need to build them stronger to take the sideways forceloads.

#199990 - 01/06/10 03:31 AM Re: Designing/Building an F16 [Re: pilgrim]  
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I think Phill Brander still supplies the Blade F16 plywood plans?

The measurements you need is from bow to chainplate, bow to main beam, bow to daggerboard and bow to rear beam.


1: Layup schedule. I can not advice you there.

2: Unless you have a way to add a fillet and glass tapes on the inside of the hull after putting the deck in place, I would do a shear stringer. I am comfortable with wood stringers. Alternatively a flange of some form. At least you need some extra glue surface area to stop the deck from popping off.

3: 10mm bulkheads are overkill. 4mm ply with cutouts will do. Foam/carbon is lighter, but I can not help you with the laminate schedule. I have done some foam/glass bulkheads and they did fine on a Tornado, but I am not comfortable on advicing you on foam/carbon/glass.

4: Ply is a possibility, or a nice spruce or WRC plank with some hefty reinforcement in fibers. If going with foam/carbon, you will want to make this part as stiff and strong as possible to minimize flexing and wracking.

5: If I was to do carbon chainplates I would do it like Farrier does. Be careful with alignment and size it for shock loads.
http://www.f-boatmart.com/images/P/F-22chainplate400-01.jpg

6: High aspect ratio, symmetric. Important part of the boat to get right and with high quality on the build and surface. Asymmetrical have been tried in other classes and have not paid off sufficiently yet, except in the C-class AFAIK.

7: Yes.

8: Not neccesarily. Depends on your layup schedule.


To get tips on layup schedules you could try getting hold of guys like Bill Vining, Kevin Cook etc here on catsailor.com. Remember that what you get here is advice given with good intentions. The advice might be spectacularly wrong and lead to catastrophic failures..

#200007 - 01/06/10 09:37 AM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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Rolf,
I sent 2 message to Phil through the forum message utility but didnt receive any reply. Will try again.

Thanks for your reply. The layup I use is based on the LR2 layup with the extra strength of doublers in the middle part of the boat.

Think I will go with the timber sheer clamp but use carbon/h160 foam/carbon bulkheads and maybe composite chainplates.

Shane



#200023 - 01/06/10 11:59 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Hi pilgrim,

1) Unless I know the loads and required stiffness, I would use a symetrical sandwich (i.e. 0/+-45/90 inside and outside) with the most fibres in direction of the main loads (from stern to bow?) but not too far from 30%/40%/30%.
If I understand you right, you want to use 200g inside and 200g outside, and midships reinforced by another 200g + 200g? Sounds a bit oversized. I would locate the areas where you need reinforcement (i.e. between the beams, along the keel, where you put the feets for trapezing and righting, around any force introduction. You can use glass instead of kevlar for insulation, does the same as good as the other.
2) yes, timber or large radius CFRP L. It needs to be strong, hence no foam. It will add so much integrity and durability for so less weight.
3) Sandwich would be enough. Add a bulkhead under the attachement for the bridle wires as well
4) I would do epoxy plugs around the bold holes, but hardwood is also possible if protected from moisture.
5) Possible, but I would prefer metal, because it will not break, just bend, if hit. And so far I bend this on all my boats...
6) if you sail single hand: symetric, if you sail dh, you could have asymteric ones. But the boards must be slightly larger, since only one is in the water. Profile and thickness are much more important than aspect ratio, area is more important than aspect ratio. A too small board with high aspect ratio will be a bad performer. DH needs more board area than SH. You can contact me for profiles better than std NACA sections.
7) yes
8) no, but you could have and reduce the weight of the carbon clothes of the sandwich skins.

Ok some words of my background:
I am an engineer with degree in aviation and working for a larger airframe builder for preliminary aircraft design, so I am neither an expert for CFRP nor manufacturing. I have never build a boat, but some parts and repair jobs. Hence be sceptical with my input.

Cheers,

Klaus

#200033 - 01/06/10 03:23 PM Re: Designing/Building an F16 [Re: pilgrim]  
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Wouter Offline
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Try Phillbrander(at)bigpond.com

Wouter


Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
#200039 - 01/06/10 09:09 PM Re: Designing/Building an F16 [Re: Smiths_Cat]  
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thanks Klaus,

Just need to clarify..

'0/+-45/90 inside and outside" you mean either 0/90 inside and outside OR -45/+45 inside and outside but not a mixture?
I was following LR2 A class cat layup which seems a reasonable compromise between longitudinal strength and torsional resistance.

What would you recommend for the boards for this Double hander? Size and profile? I have software called Profili with which I can plot foil sections. I have most of the common sections and can donwload if you give me a source or if you provide me a .dat or.txt file. I will send you an email.

Thanks


#200041 - 01/06/10 09:23 PM Re: Designing/Building an F16 [Re: pilgrim]  
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Brisbane, Queensland, Australi...
Originally Posted by pilgrim
I tried to contact a designer but no response. I would even buy a set of plans for reference but nothing modern seems available eg Blade or Viper era. I took some measurements from a Viper because I plan to use Viper sailplan and mast. Chainplate distance from main beam = 68 cm, main beam to rear beam 2m.

Questions

1. please critique my layup plan. Using 200 gm per m carbon cloth over Divinycell H80 overall, with 30g /m glass over that for a better finish. 0/90 deg orientation on th eoutside , -45/+45 inside of the hull.

Doubler of 200 g carbon starting 2m from tip of bow to 1m from transom 0/90deg orientation .

Deck doubler of 200g carbon starting 1.5m from bow tip to transom 0/90 deg orientation.

Local reinforcement of 200g /sq m cloth under beams and chainplate area -45/+45 deg oreintation. Local reinforcement of 300g/ kevlar under beams, chainplate and forestay anchor point to insulate metal from carbon and provide protection.

2. Should I have a sheer clamp to attach the deck? Timber? or Divinycell foam?

3. Bulkheads under Main Beam and Rear beam. Should I use plywood ( 10mm? ) or 200g carbon/H160 foam/carbon sandwich ?

4. Deck hardpoint under the beams - should I have 10mm plywood replacing the H80 foam or can I use H160 to replace the H80 foam?

5. Thinking of a 10mm diameter solid carbon extrusion covered in kevlar for a sidestay anchor instead of a 2,5mm stainless chainplate. More for the 'cool' factor but also to avoid crevice corrosion in the stainless steel. Worth the trouble for the cool points?

6. Broad centreboard like the Taipan or High Aspect ratio like the Viper? Asymetrical or sysmtrical foils?

7. Should there be a bulkhead at the chainplate position?

8. Do I need diagonal stringers between bulkheads as a hull stiffener and to give torsional strength?

Thanks in advance

6.


1. Wouldn't bother with the glass for wear, except maybe right down the keel say 50mm each side. Consider 45/45 inside and out for torsional stiffness. 200gsm carbon should be enough all-round although maybe consider some carbon unis from bridle to cb case along the inboard and outboard sheers (check out CST's new carbon flat bar pultrusions). You'll likely not need the extra layers of carbon. Don't forget to take the cb case opening to single skin, probably 3-5mm thick will be enough.

Depending how quickly you are doing the hull laminates, the epoxy filler screed can be laminated straight over before it cures. Less sanding (the most painful task in boat building) and a better (chemical) bond between the foam and skins.

You haven't mentioned the core thickness? This will ofcourse impact some answers.

2. Yes for sheer clamp, at the very least for locating the deck and controlling the glue while laminating the sheer. As said above, an "L" of carbon is probably the best, can kill two birds with one stone and avoid the sheer stiffener step above.

3. Use a sandwich laminate for framing. See the frames from my home build for what I consider a neat idea (ring frame with a diagonal brace of carbon unis in tension when on one hull). Think the photos are on the F16 website.

4. I prefer a resin soaked plywood and single skin laminate for hardpoints but only because I've never bothered to buy really dense foam for the small number of areas. Either should work in theory.

5. Plenty of ways to do chainplates. May I also suggest carbon plate (c-plate) as an option, but make it very thick.

6. High-ish aspect ratio cb. Buy some off the shelf if you've got the dollars, much easier to get right first time.

7. There should be a bulkhead at the forward or aft end of the cb case which should be close enough to the chainplate to provide enough support. If it is too far away then consider a ring frame that has plenty of depth at the chainplate, and thinner depth elsewhere. As said above, add a frame at the bridle too.

8. I'm not sure what you mean by diagonal stringers, but anyway, you shouldn't need any stringers. Firstly you are using a cored laminate which does the job that stringers typically do, and secondly with a 45/45 skin or two it won't need to be diagonal, you'll get plenty of torsional stiffness from the skins. Only reason you'd need a stringer is if you're core is very thin, and then only to cut the hull panel sizes down.

Just read the other responses and I agree with them too. Love that F22 chainplate, brother has something similar on 12' skiff, but it straddles a frame.

Last edited by ncik; 01/06/10 09:37 PM.
#200045 - 01/06/10 11:14 PM Re: Designing/Building an F16 [Re: ncik]  
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If you need C-plate for chainplates Shane, XSP@NSC have plenty of this.

#200047 - 01/07/10 01:19 AM Re: Designing/Building an F16 [Re: ncik]  
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pilgrim Offline
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Ncik,
Good idea to use some unidirectional on the deck, that will take care of the compression stress. Iwasn't going to have the deck at the centreboard opening single skin but I was goin to use H160 foam instead of H80 foam. The whole boat is mostly Divinicell H80 foam 10mm thick ( 80kg/ sq m density ) except for high stress areas which have H160 foam.
I'll probbaly go with the timber sheer clamp since its easier to do.

The diagonal stringers I proposed run between bulkheads and ring frames diagonal to the axis of the boat so that the boat works like a truss. But I guess if I go with the -45/+45 layup on the inside, the fibers will are in the correct orientation.

Yes that chainplate is really cool but a bit overkill on a 12ft skiff... think I will do one to keep up with the Joneses. Yacht Bling...

Shane

#200048 - 01/07/10 04:07 AM Re: Designing/Building an F16 [Re: pilgrim]  
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I meant to have
a 0/90 fabric and a +-45 fabric outside
and a 0/90 fabric and a +-45 fabric inside.
There are tow ideas behind:
1) Having the same layup scheme in- and outside will not cause any bending, warping, etc. if loads are applied. (If you pull on an asymetric sandwich, it will bend, because one skin is stiffer in the direction of the load than the other)
2) Assuming that impact loads are the most critical case, I proposed to have an nearly isotropic layup (0/+-45/90 fibres), because I think it is the best for that case, but I might be wrong. I would build small square testpieces and make impact tests to find the answer)

Regarding the boards, I would start from the an existing F16 (since they have all the same sail area and mast height), check which one has the smallest area and is regarded as a good double hander in light and strong winds.
In Profili you will have plenty of sections, but probably none designed for a beach catamaran. When I broke the rudder of my friends T, I redesigned NACA 4 digit foils (e.g. NACA 0012) from 8 to 14% thickness by changing nose radius and max thickness location, to improve maximum lift (which allows to reduce board area), cavitation and drag (it is always a trade off, you can improve two of them but worsen the other one). Since my friend complaint always about cavitation we select a board with better cavitation and lift with equal drag than a NACA section. I still should have the data on my computer, so I can send sectional data, if you tell me, which NACA foil would be your starting point (I need it as reference point) and which of the parameters you want to improve.

Cheers,

Klaus

#200094 - 01/07/10 06:35 PM Re: Designing/Building an F16 [Re: Smiths_Cat]  
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You are suggesting 2 layers of cloth but I am only planning to have one layer of 200g/sqm outside and inside. Most people think thats enough and I cant get a lighter cloth economically. A lighter carbon coth would cost more because I neeed 2 layers.

I'll probably go and measure some daggerboards tomorrow..
NACA 0012 would be a good starting point since I know its been used for this purppose before. And NACA 0015 for the rudder...

I thought we dont go fast enough for foils to cavitate... Are you modifying the foil for a higher critical angle so the foil doesnt stall? Or at least to minimise the laminar separation bubble..

Another question I want to ask you since you are working in aviation. Do you think it would help rudders work at higher angles if we introduced a turbulator at the leading edge. EG A strip of sandpaper glued to the leading edge or even roughing the LE with 60 grit sandpaper?

Shane

#200095 - 01/07/10 06:43 PM Re: Designing/Building an F16 [Re: pilgrim]  
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pilgrim Offline
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An interesting fact was brought up to me by the Technical engineer for Divinycell. Priming H80 foam takes 300gram of epoxy per sq metre... thats 300g x 8.5sq m for the hull's outside alone... 2.55kg! Another 2.55 kg for the inside as well...

Weight of hull calculation
cloth inside and outside (200g/sqm ) = 3.4kg
epoxy to saturate cloth = 3.4kg
Diviny cell H80 10mm thick = 6.8kg
Epoxy for priming both sides = 5.1kg
Reinforcement ( estimated ) 1.3kg

Total = 20kg



#200105 - 01/08/10 02:55 AM Re: Designing/Building an F16 [Re: pilgrim]  
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20kg before you put fittings, daggerboard well, bulkheads, deck possibly etc. into the hull?

#200131 - 01/08/10 09:13 AM Re: Designing/Building an F16 [Re: Rolf_Nilsen]  
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pilgrim Offline
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Rolf,
I'm including the deck in the 20kg but not the daggerboard case and the fittings so maybe 22kg total. What are you expecting for your Blade? The priming and the amount of epoxy for fairing is what is adding on the kilos..

Last edited by pilgrim; 01/08/10 09:14 AM.
#200138 - 01/08/10 12:30 PM Re: Designing/Building an F16 [Re: pilgrim]  
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Hi pilgrim,

Ok, if you cant get lighter than 200g/sqm your original layout might be a good solution in fact. Didn't know you are limited by availability...

Cavitation depends on speed and load... most people think, that the rudders stall while sailing fast downwind, but actually going 17kts and keeping the boat on course let the boards cavitate (sometimes). If you see bubbles in the water it is cavitation. Some are from the tip vortex, you can´t avoid that, but if you see bubbles at the leading edge, than is cavitation. The cavitation triggers than the stall. A good foil will not cavitate, some designers reduce thickness to achieve that, but your rudder will be less strong or must be build heavier and it will have a lower maximum lift coefficient, hence needs to be larger.

Quote
Another question I want to ask you since you are working in aviation. Do you think it would help rudders work at higher angles if we introduced a turbulator at the leading edge. EG A strip of sandpaper glued to the leading edge or even roughing the LE with 60 grit sandpaper?


Water has a higher viscosity than air, hence the Reynoldsnumbers are higher. That's why dedicated RC plane foils are not suited for boards and rudders. Classic airplane foils as the NACA 00xx works once you are fast enough without turbulator.

IMO boards and rudders will never have a laminar boundary layer, sinvce the surface water itself is already turbulent. Hence the foils which I designed are all turbulent foils.

Hope my answer wasn"t too nerdy...

Cheers,

Klaus

#200139 - 01/08/10 12:37 PM Re: Designing/Building an F16 [Re: pilgrim]  
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The main weight driver is the foam, because it is heavy and soaks resin. With honeycomb you could save a lot. But 20kg is already at the lower end. Are you vacuum bagging?

Cheers,

Klaus

#200185 - 01/09/10 10:30 AM Re: Designing/Building an F16 [Re: Smiths_Cat]  
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Klaus,
Can you send me the .dat file for your modified NACA0012 section?

NO, I'm not vacuum baggin yet but I hope to do so soon.

Shane

#200219 - 01/10/10 09:30 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Actually there are many possibilities depending on your target. To avoid confusion I selected one, which has about 4% more lift, slightly less drag and 4% less tendency for cavitation (although I think it is not necessary for a board).
You can either reduce the board area (best bz redicing chord and keeping span) by 4% or profit from the better manouverability at low speeds (e.g. at the start line).
The pictures shows you the difference between the NACA 0012 at the modified section. The new section has the thickness more forward. Gives you an impression how sensitive a foil is too surface quality.

Cheers,

Klaus

Attached Files
p122510.jpg (988 downloads)
#200246 - 01/10/10 08:28 PM Re: Designing/Building an F16 [Re: Smiths_Cat]  

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Originally Posted by Smiths_Cat
The main weight driver is the foam, because it is heavy and soaks resin. With honeycomb you could save a lot. But 20kg is already at the lower end. Are you vacuum bagging?

Cheers,

Klaus


10mm is quite thick for your foam can you get something thinner? 6mm would take almost 3kg out of each hull.

#200253 - 01/11/10 01:20 AM Re: Designing/Building an F16 [Re: ]  
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pilgrim Offline
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Klaus,
Thanks, I will use it for the dagger board. I ran the NACA 0012 through Profili and the Coefficient of Lift is terrrible after the AoA gets more than 14 degrees... I wonder if thats the software limitation or the airfoil limitation. Going to NACA 0015 buys you another 2 degrees to 16 degrees before Cl goes south too. Change in Drag with AoA 1s linear but climbs steeply after about 8 degrees... shows how gentle you should be with the rudder.

Scarecrow,
I followed the LR2 project in the A cat class and this is what they used. I tried a sheet of 6mm and it is really floppy before the carbon is applied. The 10mm is much easier to use and gives a n1ce fair hull when you glue it up on the mold. I'm still on target to get under 23 kg and my big problem is laying up the cloth on the vertical sides inside the hull.... Its a major pain!

Shane

Last edited by pilgrim; 01/11/10 01:20 AM.
#200281 - 01/11/10 12:23 PM Re: Designing/Building an F16 [Re: pilgrim]  
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Be carefull when comparing 2D with 3D aerodynamic data. The angle of attack will be higher in 3D (over 20°) than on 2D, but the cLmax is smaller, because the slope is lower. And take the right Reynoldsnumber (e.g. 500000) and turbulence level (n=3)as it has a huge effect. Thicker airfoils have higher cLmax, but more drag and are more prone to cavitation, which is more important for a rudder than cLmax. Hence I modified a 16% thick Naca section for the T to get the cavitation right, of course we had higher drag... Can send this you as well, if you want

#200282 - 01/11/10 12:26 PM Re: Designing/Building an F16 [Re: Smiths_Cat]  
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seems that I didn't manage to attach the .dat file.
So here is 12% thick board section:

p122510
1.000000 0.001278
0.993619 0.002110
0.982901 0.003491
0.970676 0.005040
0.956886 0.006757
0.941596 0.008624
0.925004 0.010608
0.907383 0.012669
0.889016 0.014769
0.870139 0.016879
0.850929 0.018979
0.831505 0.021054
0.811942 0.023098
0.792289 0.025106
0.772578 0.027076
0.752827 0.029006
0.733049 0.030897
0.713254 0.032747
0.693449 0.034557
0.673639 0.036325
0.653830 0.038051
0.634027 0.039734
0.614233 0.041373
0.594456 0.042967
0.574699 0.044514
0.554967 0.046011
0.535267 0.047458
0.515606 0.048849
0.495989 0.050184
0.476425 0.051458
0.456922 0.052667
0.437490 0.053806
0.418139 0.054872
0.398883 0.055857
0.379734 0.056757
0.360712 0.057565
0.341835 0.058272
0.323128 0.058872
0.304621 0.059355
0.286349 0.059713
0.268359 0.059937
0.250707 0.060017
0.233461 0.059945
0.216696 0.059709
0.200480 0.059296
0.184876 0.058701
0.169948 0.057921
0.155758 0.056960
0.142359 0.055829
0.129798 0.054544
0.118103 0.053128
0.107284 0.051605
0.097330 0.050001
0.088210 0.048340
0.079877 0.046643
0.072275 0.044926
0.065339 0.043201
0.059008 0.041478
0.053220 0.039761
0.047918 0.038053
0.043050 0.036355
0.038571 0.034665
0.034441 0.032982
0.030626 0.031303
0.027095 0.029624
0.023823 0.027940
0.020790 0.026247
0.017978 0.024540
0.015373 0.022812
0.012966 0.021058
0.010750 0.019271
0.008722 0.017445
0.006881 0.015574
0.005237 0.013650
0.003784 0.011677
0.002568 0.009636
0.001540 0.007555
0.000799 0.005422
0.000291 0.003251
0.000022 0.001085
0.000022 -0.001085
0.000291 -0.003251
0.000799 -0.005422
0.001540 -0.007555
0.002568 -0.009636
0.003784 -0.011677
0.005237 -0.013650
0.006881 -0.015575
0.008722 -0.017445
0.010750 -0.019271
0.012966 -0.021058
0.015373 -0.022812
0.017978 -0.024540
0.020790 -0.026247
0.023823 -0.027940
0.027095 -0.029624
0.030626 -0.031303
0.034441 -0.032982
0.038571 -0.034665
0.043050 -0.036355
0.047918 -0.038053
0.053220 -0.039761
0.059008 -0.041478
0.065339 -0.043201
0.072275 -0.044926
0.079877 -0.046643
0.088210 -0.048341
0.097330 -0.050001
0.107284 -0.051605
0.118103 -0.053128
0.129798 -0.054544
0.142360 -0.055829
0.155758 -0.056960
0.169949 -0.057921
0.184876 -0.058701
0.200480 -0.059296
0.216697 -0.059709
0.233462 -0.059945
0.250707 -0.060017
0.268359 -0.059937
0.286349 -0.059713
0.304621 -0.059355
0.323128 -0.058872
0.341835 -0.058272
0.360712 -0.057565
0.379734 -0.056757
0.398882 -0.055857
0.418139 -0.054872
0.437490 -0.053806
0.456922 -0.052667
0.476425 -0.051458
0.495989 -0.050184
0.515606 -0.048849
0.535267 -0.047458
0.554967 -0.046011
0.574698 -0.044514
0.594456 -0.042967
0.614233 -0.041373
0.634026 -0.039734
0.653830 -0.038051
0.673639 -0.036325
0.693449 -0.034557
0.713254 -0.032747
0.733049 -0.030897
0.752827 -0.029006
0.772578 -0.027076
0.792289 -0.025106
0.811942 -0.023098
0.831504 -0.021054
0.850929 -0.018979
0.870139 -0.016879
0.889016 -0.014769
0.907383 -0.012669
0.925004 -0.010608
0.941596 -0.008624
0.956886 -0.006757
0.970676 -0.005040
0.982901 -0.003491
0.993619 -0.002110
1.000000 -0.001278

Cheers,

Klaus

Last edited by Smiths_Cat; 01/11/10 12:29 PM.
#200388 - 01/13/10 09:26 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Originally Posted by pilgrim
An interesting fact was brought up to me by the Technical engineer for Divinycell. Priming H80 foam takes 300gram of epoxy per sq metre... thats 300g x 8.5sq m for the hull's outside alone... 2.55kg! Another 2.55 kg for the inside as well...

Weight of hull calculation
cloth inside and outside (200g/sqm ) = 3.4kg
epoxy to saturate cloth = 3.4kg
Diviny cell H80 10mm thick = 6.8kg
Epoxy for priming both sides = 5.1kg
Reinforcement ( estimated ) 1.3kg

Total = 20kg




Pilgrim,

I think this is very cool project and am glad you are sharing it with us.

Here are a couple of the issues I see in this process
Have you fully weighed your materials?
• H80 core will vary 25% in actual density. Acceptable density for this range will span the full difference between the H60 and H100
• In theory it takes 300 g of resin to seal the face of the core. We have found the H80 typically takes 20% more as its surface roughness is very high. With hand lam you can under coat the core, but this may cause long term life issues. Cores with a finer surface texture like Rohacell or certain grades of corecell will take significantly less resin but are more expensive.
• Non spec fibers have a weight tolerance of 10%
• Hand lamination and maintaining a fiber/glass ratio is a crap shoot unless you have done it A LOT
• Do not underestimate the weight of the finish – Fairing compound and paint. Paint will be about 2 kg alone. (half gel coat weight) The weight of the fairing depends on how good you want the thing to look and how much you get tired of sanding.
It matters not at the end of the day, but weight is not that easy to control no matter the process. Some of the builders have enough materials they can mix and match lots to keep things tight, or have a relationship where they can not accept certain batches of materials that a home builder might have to.

On the laminate, is this a sloop or Uni rigged boat? Sloop rigged configurations will have significantly more loads and if you are using the LR A class as your model and A has almost no load compared to a 2 up sloop rigged F16. Adding plenty of material to inside hull face between the bridal and the front beam is critical. Hull failures are almost always in compression. Compression resistance is mostly a function of the thickness. Carbon is stiffer than glass but you can get into problems as builders cut to single layers for the carbon and it is difficult to keep it in column.
Single skin also may be great for the design while sailing but will be very fragile, especially with H80 core. Heel dents and damage from shore/rollers and trailers will be an issue. Take very good care of this boat. An A has single skin but at 75 kg is a lot easier to move around.

Best of Luck

#200401 - 01/13/10 11:40 AM Re: Designing/Building an F16 [Re: mini]  
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You got my curiosity going to the point that I had to get up and go downstairs to my shop to look at the Divinicell I have in my possession, to see if these claims of a "rough surface" have any merit. After using boxes and boxes of 1-1/2" H130, ¾” H100, ¾” & ¼” H80, ¾” H60, and ¾” H45 I have to ask if we are talking about the same Divinicell? Are you dealing with seconds? I have never seen density variances of 25% on any of their products...

Looking at the fine cell structure of H80 in front of me it would seem that attempting to "fill the open cells" with bog prior to glassing may be something that makes sense academically, but does it translate to any appreciable weight savings in actual construction?

After bogging you have to go back and impregnate the cloth using enough resin to get a complete bond to the bogged surface...and your resin system better have a very long pot life if you have aspirations of bogging the entire hull surface and then laminating the cloth while the bog is still wet.
1) Who is this technical engineer for Divinicell that made this claim and where on their web site can this information be verified?
2) What is the ratio of resin to glass bubbles/micro balloons that is being used?
3) If it takes 300 grams of pure resin to fill in the cut cells of a sq/meter of material how many grams of bog does it take to fill in the cut cells? What is the resulting proposed saving of weight?
4) Does the 300 grams /per/sq/m consider only one side of the foam or both the front and back surfaces of a sandwich?
5) Is this something that only works at the desk with a calculator? Or will it be reproducible in the work shop?
6) Will a carefully prepared small test panel (even up to a full sq/meter) give you an accurate sample, taking into consideration the difficulty of reproducing this on the large skin surface area of a hull unless you employ a small army of expert laminators working in unison?
7) Your bond is only as strong as its weakest link. Resin/Filler/Foam. Is the bog stronger or weaker than the H80?
8) Could the very thing you are trying to avoid (filling in the cut cells of the foam with resin) actually work against you? Could having the resin filling the cells actually give a better mechanical bond, and possibly increase stiffness a very slight amount? When using West System resin on wood do they call for bog over the wood to prevent the resin from soaking into the grain? No, just the opposite. Almost any adhesive will perform better when the bonding surfaces are roughed up, why should this scenario be any different? In the commercial use of Divinicell that I have participated in the past, we never used bog between two structural components for concerns of delamination.(This last comment is contingent on the bog being weaker than the particular PVC cross linked structural foam being used).

If one is using open cell Styrofoam bogging is imperative, but the closed cell???

Robert

#200459 - 01/14/10 08:37 AM Re: Designing/Building an F16 [Re: mini]  
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mini,
No, I didnt weigh the foam but I am keeping track of the epoxy I use. So far I've used 3.75kg for the outside of the hull alone

1.5kg to wet the cloth ( 7.5 sq m x 0.2 kg/m )
2.25 kg to fill the foam ( 7.5 sq m x 0.3 kg/m )

Yes, I am fully expecting to add weight during fairing but you know, building a boat is not about perfection, good enough will do. Purists will throw up their hands with my philosophy but working alone and at home, part time, the greatest mistake is to get so caught up with perfection that you get burned out and dont finish the project. I'll try to keep the weight down but a sound structure is more important.
Its a sloop rig and I'll be reinforcing 'midships with an extra layer of carbon. Compression failure is something I am very conscious of so the deck and the inside of the hulls will have extra reinforcement. This extra reinforcement is something the LR2 didnt have so this cat will be at least twice as strong as the A cat. In order to keep the weight down I will have only one layer on the outside of the hulls so if I get T boned I will have to do repairs for sure...everything is a compromise.

Shane

#200460 - 01/14/10 08:45 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Question 3) IF you use a lightweight filler, the density of the epoxy filler mix is less so you have less weight for the same volume and you might have 250g/ sq m per side added weight.
4) The 300g/sq m is per side so 600g/sq m for both sides.

7) I dont know what will happen if you dont prime the faom but when I removed a section of foam to add a piece of plywood for the chainplate I found the epoxy soaked foam really tough and the bond between foam and carbon reassuringly tough too.. I didnt use vacuum so I was pleased at that...

Shane

PS from the Divinycell Tech Sheet..

Primer coverage rates
H60 - 360g/sq m
H80 - 300g/sq m
H100 - 275g
H200 - 200g/sq m

Looking at the numbers I see that getting the H60 doesnt save you a lot of weight because you have to put much more epoxy to prime it.

1 sq m of H60 primed both sides = 600g + 360g +360g = 1320g
1 sqm of H80 primed both sides = 800g + 300 +300 = 1400g
1 sq m of H100 primed both sides = 1000g + 275g +275g = 1550g

H80 seems to be a more optimal foam than H60.

Last edited by pilgrim; 01/14/10 09:42 AM.
#200461 - 01/14/10 09:11 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Matt M Offline
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Originally Posted by pilgrim
mini,
No, I didnt weigh the foam but I am keeping track of the epoxy I use. So far I've used 3.75kg for the outside of the hull alone

1.5kg to wet the cloth ( 7.5 sq m x 0.2 kg/m )
2.25 kg to fill the foam ( 7.5 sq m x 0.3 kg/m )



Pilgrim,

50% fiber content and about 1 oz/ sf (300g/m2) is still pretty typical for hand lamination.

You do not save weight, but by wetting the foam and then working to press the fiber through the resin rather than the other way it works a bit easier, especially with carbon as the carbon is a lot more work to get properly wet out. With some practice you can get 60% fiber content, 70 will require bagging.

On the material weights I have to agree with mini.

They make the core in a huge bun with the heavy density material at the bottom and the light at the top. It gets sliced in ranges and we have seen variance easily as high as 25% from order to order. Their spec sheet says 10% typical. There used to be a Diab University or some such name. The H80 has a 1 oz per sf value and adding cuts, perfs, or the groove core for infusion can be more than double that in practice. We have how to sheets that all use these same numbers from them, but I do not know if it is on the web site. This is not something to brag about. There are a lot of other choices in core, some take even more resin. Some cores have a much finer cell structure and take less. We have proven these numbers in test lams and in practice. Even the very fine cell structure on the expensive Rohacell stuff only save maybe 25% in resin for the wet out.

By the way, running test samples of your parts is a very good idea. This will tell you the real weights and usually point out trouble spots like you had bunching the fiber on the sides.

Good luck

#200462 - 01/14/10 09:51 AM Re: Designing/Building an F16 [Re: Matt M]  
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I am picturing the giant foam bun being sliced like a loaf of bread.... the foam structure is like bread too...epoxy spread like butter on bread.

When I got the foam they told me a few sheets had minor imperfections but the sheet was within spec... I wasnt happy because at that price I should get perfect sheets! Anyway, the foam was on the way so I let them placate me with a 5% discount.

#279267 - 05/29/15 04:37 AM Re: Designing/Building an F16 [Re: pilgrim]  
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Abraham Offline
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I think you can easily find brazil white wood. It is also good for sail. I also want to sail but never try in my life. Because i scared. But one day i will do. Hop that dy will come soon in my life.

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